1. Field of the Invention
The present invention relates to a tantalum chip type capacitor device used for a portable device such as a telephone that is allowed to have a fusing feature.
2. Related Art
A tantalum chip type capacitor device has been used for a part such as a power source circuit for a portable device requiring a large capacity such as telephones, laptop computers, and miniaturized, lighter weight, and thin-shaped tantalum chip type capacitor devices have been demanded and a fusing feature has also been sought in terms of being used as a power source circuit.
FIG. 9 is a cross-sectional view showing a capacitor element of the chip tantalum capacitor.
As shown in FIG. 9, the capacitor element 1 is made in such a manner that tantalum (Ta) 2 in the form of metal powders and a tantalum bar for drawing out a lead wire are subjected to pressurization, molding and vacuum hardening, and in the surface thereof, a tantalum oxide film (Ta2O5) 4 used as a dielectric body is formed by electrochemical anodization.
As an electrolyte, a solid manganese dioxide layer (MnO2) 5 is formed on the dielectric body by the thermal decomposition of manganese nitrate. In order to allow this manganese dioxide layer 5 to have thereon an electric connection, the graphite layer 6 is provided. On the graphite layer 6, a cathode lead 8 is formed by use of a silver covering material 7 and a conductive adhesive agent.
FIG. 10 is a schematic view of a conventional chip tantalum capacitor device using the capacitor element 1. As shown in FIG. 10, the anode terminal 9 which is bent in the shape of an overturned latter 1 is welded to the tantalum bar 3 of the capacitor element 1 provided as described above at a welding point 10. The cathode terminal 11 bent in a complicated manner is pressure-bonded to the cathode lead 8 formed of conductive adhesive agent. Furthermore, the capacitor element 1, the anode terminal 9, and the cathode terminal 11 are partially exposed to the exterior to be molded by an epoxy resin 12, thereby forming the chip tantalum capacitor.
As described above, bent and intricately-shaped electrode elements have been used for an anode lead and a cathode lead of conventional chip tantalum capacitor devices, thus requiring man-hours and cost. Additionally, bent and intricately-shaped electrode elements have been used, therefore, miniaturized, lighter weight and thin-shaped chip capacitors cannot be achieved.
If the conventional chip tantalum capacitor has a fusing feature, the capacitor cannot be prevented from being larger and thicker because of the inclusion of the fusing feature, which is contrary to the need for a miniaturized, lighter weight and thin-shaped chip capacitor. In this case, additional labor has been required for including the fuse.